"In July, around 300 elephants had died from cyanide poisoning in Hwange and were discovered by a group of hunters who flew over the area," Johnny Rodrigues, chairman of the Zimbabwe Conservation Task Force told AFP.

The figure is much higher than an earlier estimate last week that about 100 Zimbabwe elephants had been poisoned.

Government officials were unable to confirm the latest figure from the Zimbabwe Conservation Task Force.

Four poachers have been arrested and sentenced to 15 years each for the crime, the AFP reported.

Rodrigues accused local authorities of downplaying the elephant death toll as part of "a big cover-up," to avoid prosecuting the criminals who were responsible for the operation.

"The problem is that a big cover-up is going on," Rodrigues said. "Those who have been arrested and convicted are the small fry who are being used as scapegoats while the big and dangerous fish are untouched. These include politicians and big business people."

Local authorities have given villagers till the end of the month to turn over cyanide they might have, otherwise suspects will face prosecution.

The poachers appear to have been local residents, considering that following the arrests, local traditional leaders asked for leniency, claiming their actions were not motivated by greed, but by desperation due to poverty.

Elephant ivory tusks are prized throughout Asia and the Middle East, where they are used for ornaments as well as in medicine.

Since 1989, the international ivory trade has been largely outlawed around the world due to the drastic decline of Africa's elephant population by the mid-twentieth century, the AFP noted.

According to wildlife experts, despite the prohibition, every year approximately $10 billion is exchanged in the illegal international ivory trade.